It’s odd to think about, but did you know that the Touch ID sensor on your iPhone makes noise? If you hold an iPhone 6 or 6 Plus up to your ear in a quiet room and touch the Touch ID sensor, then you will hear a very faint clicking sound emitting from the vicinity of the sensor. It’s just another weird fact gleaned from the /r/apple this morning.

When I stumbled upon this thread, I just had to verify it for myself. I took my Touch ID equipped iPhone 6 Plus into a quiet location, placed the device up to my ear close to the Touch ID sensor, and put my finger on the sensor while the phone was unlocked. At first I didn’t hear anything, because I expected it to be more audible than it actually is, but after a while—after some fine ear tuning—I was able to hear the sound.

The best way that I can describe the sound is that it’s a clicking noise, a clicking noise that’s very repetitive until you release your finger from the sensor. It sounds very much like the noise that occurs when you turn on a gas stove’s pilot light.

The noise is extremely faint, and won’t be heard in a room with a lot of ambient noise. In fact, it’s so faint, that you’re just going to have to take my word for it, as there’s no way that any of my microphones are sensitive enough to pick up the sound.

But seriously, try it out, and let me know if you hear anything. I tried it on my iPhone 5s as well, but from what I gather on the Reddit thread, it only works on newer devices like the 6 and 6 Plus. I’m assuming this is because the iPhone 6 uses the Touch ID sensor all of the time for Reachability, but that’s just an assumption on my part.

It’s kind of a weird little fun fact, but nevertheless, tell me what do you think.

Update: @diogopires21 has recorded the sound and uploaded it to YouTube: